Main hollow channel insulation structure of 35kV level layer type winding oil-immersed transformer

Abstract

The utility model discloses a main air channel insulation structure of a 35kV level layer type winding oil-immersed transformer, which comprises an iron core, a low-voltage coil and a high-voltage coil are sequentially wound on the peripheral side of the iron core from inside to outside, and a first supporting strip, a first paperboard layer, a second paperboard layer, a third paperboard layer and a second supporting strip are sequentially filled in a main air channel between the high-voltage coil and the low-voltage coil. The upper end and the lower end of the main hollow channel are each provided with a soft angle ring, the inner ends of the soft angle rings are inserted, clamped and fastened in annular inserting grooves between the first paperboard layer and the third paperboard layer and correspondingly connected with the upper end edge or the lower end edge of the second paperboard layer, and the outer ends of the soft angle rings are laid on the end face of the high-voltage coil. According to the main hollow channel insulation structure, the radial width of the main hollow channel is reduced as much as possible, the size of a transformer product is effectively reduced, assembly is easy, the transformer assembling and processing efficiency can be improved, the manufacturing cost is reduced, and the occupied space is saved; the creepage distance between high-voltage and low-voltage wires is effectively increased, and the insulation performance between the high-voltage and low-voltage ends of the transformer is remarkably improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to transformer technical field, concretely relates to a kind of main airway insulation structure of 35kV level layer type winding oil-immersed transformer. BACKGROUND

[0002] The oil-immersed transformer of layer type winding structure has the advantages of simple structure and convenient winding compared with the oil-immersed transformer of pie type winding structure, thus, the oil-immersed transformer of layer type winding structure is widely applied in the capacity range of 35kV~1600kVA.

[0003] The transformer insulation examination project mainly includes power frequency withstand voltage, induction withstand voltage and lightning impulse, wherein power frequency withstand voltage mainly examines main insulation, induction withstand voltage mainly examines longitudinal insulation, and lightning impulse examines main insulation and longitudinal insulation, thus the main insulation structure inside transformer needs to withstand the double examination of power frequency withstand voltage and lightning impulse.The main insulation structure of the oil-immersed transformer of layer type winding structure refers to the insulation performance of main airway structure between low-voltage coil and high-voltage coil wound outside the iron core.

[0004] For example, Figures 1-2The main air channel insulation structure of a 35kV level layered winding oil-immersed transformer shown comprises a core 1, a low-voltage coil 2 and a high-voltage coil 3 are wound on the outer circumferential side of the core 1 from inside to outside, a main air channel 4 provided between the low-voltage coil 2 and the high-voltage coil 3 is internally filled with a plurality of support bars 5, a paperboard layer 6, a plurality of support bars 9 and two soft corner rings 10, the plurality of support bars 5, the paperboard layer 6 and the plurality of support bars 9 are sequentially wrapped on the outer circumferential side of the low-voltage coil 2 from inside to outside, the inner ends of the two soft corner rings 10 are correspondingly inserted and clamped and fixed at the upper and lower ends of the gap between the paperboard layer 6 and the support bars 9, and the outer end portions of the soft corner rings 10 extending out of the upper and lower ends of the main air channel 4 are bent and annularly laid on the upper and lower end faces of the high-voltage coil 3, the support bars 5, the paperboard layer 6 and the low-voltage coil 2 enclose a plurality of longitudinal oil channels 15 located inside the paperboard layer 6, and the support bars 9, the paperboard layer 6 and the high-voltage coil 3 enclose a plurality of longitudinal oil channels 15 located outside the paperboard layer 6. The upper and lower ends of the support bars 9 are respectively provided with annular stepped grooves 9-1 facing the paperboard layer 6, and the inner ends of the soft corner rings 10 are inserted into the corresponding annular stepped grooves 9-1 of the support bars 9. The upper and lower end faces of the low-voltage coil 2 are respectively provided with low-voltage end insulation layers 11, the upper and lower end faces of the high-voltage coil 3 are sequentially provided with a high-voltage end insulation layer 12 and a high-voltage end insulation layer 13 from inside to outside, and the outer end portions of the soft corner rings 10 are laid on the outer side face of the high-voltage end insulation layer 13. In order to meet the insulation performance of the main insulation structure and the creepage distance requirement between the high-voltage and low-voltage conductors, the thickness of the low-voltage end insulation layer 11 is d1=7mm, the thickness of the support bars 5 is d2=4.25mm, the thickness of the paperboard layer 6 is d3=3mm, the thickness of the soft corner rings 10 is d4=1.5mm, the thickness of the support bars 9 is d5=4.25mm, the thickness of the high-voltage end insulation layer 12 is d6=10mm, and the depth of the inner end of the soft corner rings 10 inserted into the main air channel 4 is h=60mm. The radial width of the main air channel 4 is D=d2+d3+d4+d5=4.25mm+3mm+1.5mm+4.25mm=13mm, and the creepage distance L between the high-voltage and low-voltage conductors is d1+d2+h+d4+d5+d6=7mm+4.25mm+60mm+1.5mm+4.25mm+10mm=87mm. The main air channel insulation structure of the 35kV level layered winding oil-immersed transformer has the following problems: (1) the radial width size of the main air channel is large, resulting in a large overall volume of the assembled transformer, and a large space occupied during storage, transportation and use; (2) the creepage distance size between the high-voltage and low-voltage conductors is small, resulting in poor insulation performance between the high-voltage and low-voltage ends of the transformer. Therefore, the utility model provides a main air channel insulation structure of a 35kV level layered winding oil-immersed transformer with a novel structure to solve the above technical problems. SUMMARY

[0005] The utility model discloses a 35kV level layer type winding oil -immersed transformer's main air channel insulation structure, and the compact and reasonable structure layout of the support strip, paperboard layer and soft angle ring structure filled in the main air channel inside, under the premise of guaranteeing the main air channel insulation performance, makes the radial width of main air channel as small as possible to make the volume of the transformer product assembled effectively reduces, and the overall assembly is simple, which helps to improve the assembly processing efficiency of transformer, reduces the manufacturing cost, saves the space occupied when storing, transporting and using, the inner end of soft angle ring is clamped in the annular insertion slot between paperboard layer one and paperboard layer three, so that the inner end of soft angle ring is tightly attached together with the paperboard layer, and the creepage distance between high voltage and low voltage conductors is effectively increased, thereby the insulation performance between high voltage and low voltage of transformer is improved significantly, the support strip one forms a plurality of longitudinal oil channels on the inner side of paperboard layer one, and the support strip two forms a plurality of longitudinal oil channels on the outer side of paperboard layer three, which ensures the smoothness of cooling liquid circulation in the main air channel, thereby ensuring that the transformer with the main air channel insulation structure of 35kV level layer type winding oil -immersed transformer of the utility model has good heat dissipation performance.

[0006] To achieve the above object, the technical scheme of the utility model is to design a 35kV level layer type winding oil -immersed transformer's main air channel insulation structure, including the iron core, the low voltage coil and the high voltage coil are sequentially wound from inside to outside on the outer circumferential side of the iron core, the main air channel is arranged between the low voltage coil and the high voltage coil, the main air channel is filled with a plurality of support strips one, paperboard layer one, paperboard layer two, paperboard layer three, a plurality of support strips two and two soft angle rings, the plurality of support strips one, paperboard layer one, paperboard layer two, paperboard layer three and a plurality of support strips two are sequentially coated on the outer circumferential side of the low voltage coil from inside to outside, the upper and lower end edges of the paperboard layer two are respectively recessed on the inner side of the main air channel to form annular insertion slots on the upper and lower ends between paperboard layer one and paperboard layer three, one soft angle ring is located at the upper end of the main air channel, and another soft angle ring is located at the lower end of the main air channel, the inner end of the soft angle ring is inserted and clamped in the corresponding annular insertion slot and corresponds to the upper end edge or lower end edge of the paperboard layer two, the outer end of the soft angle ring extending out of the upper end port of the main air channel is bent and annularly laid on the upper end surface of the high voltage coil, the outer end of the soft angle ring extending out of the lower end port of the main air channel is bent and annularly laid on the lower end surface of the high voltage coil, the support strip one and the low voltage coil and paperboard layer one form a plurality of longitudinal oil channels on the inner side of paperboard layer one, and the support strip two and the high voltage coil and paperboard layer three form a plurality of longitudinal oil channels on the outer side of paperboard layer three.

[0007] The utility model discloses a kind of main airway insulation structures of 35kV level layer type winding oil-immersed transformer, the compact and reasonable structure layout of bracing piece, paperboard layer and soft angle ring filled in the inside of main airway, under the premise of guaranteeing the insulation performance of main airway, the radial width of main airway is as small as possible, so that the volume of the transformer product assembled into shape is effectively reduced, overall assembly is simple, help to improve the assembly processing efficiency of transformer, reduce manufacturing cost, save the space occupied when storage, transportation and use;The inner end of soft angle ring is clamped in the inside of annular insertion slot between paperboard layer one and paperboard layer three, so that the inner end of soft angle ring both sides are tightly attached together with paperboard layer, so that the creepage distance between high-voltage wire and low-voltage wire is effectively increased, thereby the insulation performance between the high-voltage end and low-voltage end of transformer is significantly improved;The several longitudinal oil channels formed by bracing piece one inside paperboard layer one and the several longitudinal oil channels formed by bracing piece two outside paperboard layer three ensure the smoothness when cooling liquid circulates in the inside of main airway, so as to ensure that the transformer using the main airway insulation structure of 35kV level layer type winding oil-immersed transformer of the utility model has good heat dissipation performance.

[0008] Preferably, the depth h of the soft angle ring inserted into the annular insertion slot is greater than 60mm. This ensures the firmness of the inner end of the soft angle ring when inserted and installed in the inside of the main airway, effectively avoiding the soft angle ring from being pulled out of the annular insertion slot between paperboard layer one and paperboard layer three.

[0009] Further preferably, the thickness d2 of bracing piece one is 4.25mm, the thickness a1 of paperboard layer one is 1mm, the thickness a2 of paperboard layer two is 1.5mm, the thickness a3 of paperboard layer three is 0.5mm, the thickness d4 of soft angle ring is 1.5mm, and the thickness d5 of bracing piece two is 4.25mm. The sum d3 of the thicknesses of paperboard layer one, paperboard layer two and paperboard layer three is 3mm, so the radial width D of the main airway between the high-voltage coil and the low-voltage coil is 11.5mm, which is significantly smaller than the radial width of 13mm of the main airway in the traditional layer type winding oil-immersed transformer. This effectively reduces the volume of the transformer product assembled into shape, reduces the manufacturing cost, and reduces the space occupied during storage, transportation and use.

[0010] Further preferred technical solutions also have, the upper and lower two end surfaces of the low-voltage coil are respectively provided with low-voltage end insulation layer, the upper and lower two end surfaces of the high-voltage coil are sequentially provided with high-voltage end insulation layer one and high-voltage end insulation layer two from inside to outside, the outer end portion of the soft corner ring is laid on the outer side surface of high-voltage end insulation layer two, and the outer side surface of the outer end portion of the soft corner ring is flush with the outer side surface of the low-voltage end insulation layer, and the outer side surface of the outer end portion of the soft corner ring and the outer side surface of the low-voltage end insulation layer are laid with an iron yoke insulation layer.The coil two end insulation layer structure is clever and reasonable, and further strengthens the protection of the relatively weak part of the coil end insulation, improves the coil end field intensity distribution, ensures that the high-voltage transformer high-voltage coil has sufficient electrical strength to the low-voltage coil, to the iron core and to the ground, so as to ensure that the transformer can run safely for a long time.

[0011] Further preferred technical solutions also have, the thickness of the low-voltage end insulation layer is d1=7mm, and the thickness of the high-voltage end insulation layer one is d6=10mm.The high-low voltage conductor creepage distance L1=d1+d2+h+d4+h+d5+d6=7+4.25+60+1.5+60+4.25+10=147mm of the main air channel insulation structure of the 35kV level layered winding oil-immersed transformer of the utility model, compared with the high-low voltage conductor creepage distance (L=87mm) of the traditional layered winding structure of the oil-immersed transformer, is increased by 60mm, so that the insulation performance between the high-low voltage ends of the transformer with the main air channel insulation structure of the 35kV level layered winding oil-immersed transformer of the utility model is greatly improved.

[0012] Preferred technical solutions also have, the low-voltage coil and the high-voltage coil are provided with a plurality of support bars three for heat dissipation between layers in a ring shape, and the support bars three and the layers of the low-voltage coil or the high-voltage coil form a plurality of longitudinal oil channels.It is ensured that the cooling liquid can flow effectively in the gap between the layers of the low-voltage coil and the gap between the layers of the high-voltage coil, so as to help improve the cooling efficiency of the cooling liquid on the high-voltage coil and the low-voltage coil.

[0013] Further preferred technical solutions also have, the plurality of support bars one, paperboard layers one, paperboard layers two, paperboard layers three, a plurality of support bars two and soft corner rings are all fixedly arranged on the outer circumferential surface of the iron core.The fixing mode of each cladding layer on the outer part of the iron core is simple and firm, which helps to improve the assembly and processing efficiency of the main air channel insulation structure of the 35kV level layered winding oil-immersed transformer of the utility model, and prolong the service life of the transformer

[0014] The utility model has the advantages and beneficial effects that:

[0015] 1. The main air channel insulation structure of the 35kV level layer type winding oil-immersed transformer, the support strip, the paperboard layer and the soft corner ring structure filled in the main air channel are compact and reasonable in structure layout, the radial width of the main air channel is as small as possible under the premise of guaranteeing the insulation performance of the main air channel, so that the volume of the assembled transformer product is effectively reduced, the overall assembly is simple, the assembly and processing efficiency of the transformer is improved, the manufacturing cost is reduced, the space occupied during storage, transportation and use is saved, the inner end of the soft corner ring is clamped in the ring-shaped insertion slot between the first paperboard layer and the third paperboard layer, the inner end of the soft corner ring is tightly attached to the paperboard layer on both sides, the creepage distance between the high-voltage wire and the low-voltage wire is effectively increased, and the insulation performance between the high-voltage end and the low-voltage end of the transformer is improved.

[0016] 2. The thickness of the support strip is d2=4.25mm, the thickness of the first paperboard layer is a1=1mm, the thickness of the second paperboard layer is a2=1.5mm, the thickness of the third paperboard layer is a3=0.5mm, the thickness of the soft corner ring is d4=1.5mm, and the thickness of the support strip is d5=4.25mm. The sum of the thicknesses of the first paperboard layer, the second paperboard layer and the third paperboard layer is d3=a1+a2+a3=3mm, the radial width of the main air channel between the high-voltage coil and the low-voltage coil is D=d2+d3+d5=4.25mm+3mm+4.25mm=11.5mm, the radial width of the main air channel in the traditional layer type winding structure of the oil-immersed transformer is 13mm, the radial width of the main air channel is greatly reduced, so that the volume of the assembled transformer product is effectively reduced, the manufacturing cost is reduced, and the space occupied during storage, transportation and use is reduced.

[0017] 3. The thickness of the low-voltage end insulation layer is d1=7mm, and the thickness of the high-voltage end insulation layer is d6=10mm. The creepage distance L1 between the high-voltage wire and the low-voltage wire of the main air channel insulation structure of the 35kV level layer type winding oil-immersed transformer of the utility model is d1+d2+h+d4+h+d5+d6=7+4.25+60+1.5+60+4.25+10=147mm, which is 60mm larger than the creepage distance (L=87mm) between the high-voltage wire and the low-voltage wire in the traditional layer type winding structure of the oil-immersed transformer, so that the insulation performance between the high-voltage end and the low-voltage end of the transformer with the main air channel insulation structure of the 35kV level layer type winding oil-immersed transformer of the utility model is greatly improved.

[0018] 4, several said support bar one, paperboard layer one, paperboard layer two, paperboard layer three, several support bar two and soft corner ring are all fixed and covered on the outer circumferential side of the iron core. The fixing mode of each covering layer on the outside of the iron core is simple, firm and good, which helps to improve the assembly and processing efficiency of the main air channel insulation structure of the 35kV level layer type winding oil immersed transformer, and prolong the service life of the transformer. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a main air channel insulation structure of a 35kV level layer type winding oil immersed transformer in the background art;

[0020] Figure 2 is Figure 1 is a partial enlarged view of H in

[0021] Figure 3 is a main air channel insulation structure of a 35kV level layer type winding oil immersed transformer of the utility model;

[0022] Figure 4 is Figure 3 is a partial enlarged view of S in

[0023] In the figure: 1, iron core; 2, low-voltage coil; 3, high-voltage coil; 4, main air channel; 5, support bar one; 6, paperboard layer one; 7, paperboard layer two; 8, paperboard layer three; 9, support bar two; 10, soft corner ring; 11, low-voltage end insulation layer; 12, high-voltage end insulation layer one; 13, high-voltage end insulation layer two; 14, iron yoke insulation layer; 15, longitudinal oil channel; 16, annular insertion slot; 9-1, annular stepped slot. DETAILED DESCRIPTION

[0024] The specific embodiments of the utility model will be further described below in combination with the drawings and examples. The following examples are only used to more clearly illustrate the technical scheme of the utility model, and cannot be used to limit the protection scope of the utility model.

[0025] EXAMPLE

[0026] As Figures 3-4As shown, the utility model relates to a kind of main airway insulation structures of 35kV level layer type winding oil-immersed transformer, including core 1, the low voltage coil 2 and high voltage coil 3 are sequentially wound from inside to outside on the outer circumferential side of the core 1, the low voltage coil 2 and high voltage coil 3 between being equipped with main airway 4, the inside of the main airway 4 is filled with several support strip one 5, paperboard layer one 6, paperboard layer two 7, paperboard layer three 8, several support strip two 9 and two soft angle ring 10, several the support strip one 5, paperboard layer one 6, paperboard layer two 7, paperboard layer three 8 and several support strip two 9 are sequentially coated on the outer circumferential side of the low voltage coil 2 from inside to outside, the upper and lower two end edges of the paperboard layer two 7 are respectively inducted in the inside of main airway 4 to form the annular insertion slot 16 of the upper and lower two end portions between paperboard layer one 6 and paperboard layer three 8, one the soft angle ring 10 is located in the upper end of main airway 4, another the soft angle ring 10 is located in the lower end of main airway 4, the inner end of the soft angle ring 10 is inserted into the corresponding annular insertion slot 16 and is correspondingly connected with the upper end edge or lower end edge of paperboard layer two 7, the outer end portion of the soft angle ring 10 extending out of the upper end of main airway 4 is bent and annularly laid on the upper end surface of high voltage coil 3, the outer end portion of the soft angle ring 10 extending out of the lower end of main airway 4 is bent and annularly laid on the lower end surface of high voltage coil 3, support strip one 5 and low voltage coil 2, paperboard layer one 6 form several longitudinal oil channels 15 located in the inside of paperboard layer one 6, support strip two 9 and high voltage coil 3, paperboard layer three 8 form several longitudinal oil channels 15 located in the outside of paperboard layer three 8.

[0027] Preferably, the depth h of the inner end of the soft angle ring 10 inserted into the annular insertion slot 16 is greater than 60mm.

[0028] Further preferably, the thickness d2 of the support strip one 5 is 4.25mm, the thickness a1 of the paperboard layer one 6 is 1mm, the thickness a2 of the paperboard layer two 7 is 1.5mm, the thickness a3 of the paperboard layer three 8 is 0.5mm, the thickness d4 of the soft angle ring 10 is 1.5mm, and the thickness d5 of the support strip two 9 is 4.25mm.

[0029] Preferably, the upper and lower two end surfaces of the low voltage coil 2 are respectively provided with low voltage end insulation layer 11, the upper and lower two end surfaces of the high voltage coil 3 are sequentially provided with high voltage end insulation layer one 12 and high voltage end insulation layer two 13 from inside to outside, the outer end portion of the soft angle ring 10 is laid on the outside surface of the high voltage end insulation layer two 13, and the outside surface of the outer end portion of the soft angle ring 10 is flush with the outside surface of the low voltage end insulation layer 11, and the outside surface of the outer end portion of the soft angle ring 10 and the outside surface of the low voltage end insulation layer 11 are laid with iron yoke insulation layer 14.

[0030] Further preferably, the thickness of the low voltage end insulation layer 11 is d1=7mm, and the thickness of the high voltage end insulation layer one 12 is d6=10mm.

[0031] Preferably, the layers of the low-voltage coil 2 and the high-voltage coil 3 are circumferentially spaced apart by a plurality of struts three 3, which form a plurality of longitudinal oil channels 15 with the layers of the low-voltage coil 2 or the high-voltage coil 3.

[0032] Further preferably, the plurality of struts one 5, the paperboard layer one 6, the paperboard layer two 7, the paperboard layer three 8, the plurality of struts two 9 and the soft corner ring 10 are all fixedly arranged on the outer circumferential side of the core 1.

[0033] The main air gap insulation structure of the 35kV level layer type winding oil-immersed transformer of the utility model, the struts, the paperboard layers and the soft corner ring structure layout filled in the main air gap interior are compact and reasonable, under the premise of guaranteeing the main air gap insulation performance, make the radial width of the main air gap as small as possible, thereby making the volume of the assembled transformer product effectively reduce, the overall assembly is simple, help to improve the assembly processing efficiency of the transformer, reduce the manufacturing cost, save the space occupied during storage, transportation and use; the inner end of the soft corner ring is inserted and clamped in the circumferential insertion slot between the paperboard layer one and the paperboard layer three, so that the inner end of the soft corner ring is tightly attached to the paperboard layers on both sides, so that the creepage distance between the high-voltage and low-voltage conductors is effectively increased, thereby significantly improving the insulation performance between the high-voltage and low-voltage ends of the transformer; the plurality of longitudinal oil channels formed by the struts one inside the paperboard layer one and the plurality of longitudinal oil channels formed by the struts two outside the paperboard layer three ensure the smoothness of the cooling liquid when circulating in the main air gap, thereby ensuring that the transformer with the main air gap insulation structure of the 35kV level layer type winding oil-immersed transformer of the utility model has good heat dissipation performance.

[0034] The main air gap insulation structure of the 35kV level layer type winding oil-immersed transformer of the utility model is not limited to the 35kV level oil-immersed transformer, and is also applicable to oil-immersed transformers of other voltage levels (such as 15kV, 20kV, 60kV level).

[0035] The above is only the preferred embodiment of the utility model, and it should be pointed out that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the technical principles of the utility model, and these improvements and refinements should also be considered as the protection range of the utility model.

Claims

1. A main air-gap insulation structure of a 35 kV class laminated winding oil-immersed transformer, comprising a core (1), a low-voltage coil (2) and a high-voltage coil (3) being wound on the core (1) in turn from inside to outside on the outer circumferential side of the core (1), a main air-gap (4) being provided between the low-voltage coil (2) and the high-voltage coil (3), characterized in that, The main cavity (4) is filled with a plurality of support bars (5), a paperboard layer (6), a paperboard layer (7), a paperboard layer (8), a plurality of support bars (9) and two soft corner rings (10). The plurality of support bars (5), the paperboard layer (6), the paperboard layer (7), the paperboard layer (8) and the plurality of support bars (9) are sequentially wrapped on the outer circumferential side of the low-voltage coil (2) from inside to outside. The upper and lower ends of the paperboard layer (7) are respectively recessed into the inner side of the main cavity (4) to form annular insertion slots (16) at the upper and lower ends between the paperboard layer (6) and the paperboard layer (8). One of the soft corner rings (10) is located at the upper end of the main cavity (4), and the other soft corner ring (10) is located at the lower end of the main cavity (4). The inner end of the soft corner ring (10) is inserted into the corresponding annular insertion slot (16) and is in corresponding contact with the upper end or the lower end of the paperboard layer (7). The outer end of the soft corner ring (10) extending out of the upper end of the main cavity (4) is bent and annularly laid on the upper end surface of the high-voltage coil (3). The outer end of the soft corner ring (10) extending out of the lower end of the main cavity (4) is bent and annularly laid on the lower end surface of the high-voltage coil (3). The support bars (5) and the low-voltage coil (2) and the paperboard layer (6) form a plurality of longitudinal oil channels (15) on the inner side of the paperboard layer (6). The support bars (9) and the high-voltage coil (3) and the paperboard layer (8) form a plurality of longitudinal oil channels (15) on the outer side of the paperboard layer (8).

2. The main void insulation structure of a 35 kV class laminated winding oil immersed transformer as claimed in claim 1, wherein, The depth h of the inner end of the soft corner ring (10) inserted into the annular insertion slot (16) is greater than 60mm.

3. The main void insulation structure of a 35 kV class laminated winding oil immersed transformer as claimed in claim 2, wherein, The thickness d2 of the support bar (5) is 4.25mm, the thickness a1 of the paperboard layer (6) is 1mm, the thickness a2 of the paperboard layer (7) is 1.5mm, the thickness a3 of the paperboard layer (8) is 0.5mm, the thickness d4 of the soft corner ring (10) is 1.5mm, and the thickness d5 of the support bar (9) is 4.25mm.

4. The main void insulation structure of a 35 kV class laminated winding oil immersed transformer as claimed in claim 1, wherein, The upper and lower end surfaces of the low-voltage coil (2) are respectively provided with low-voltage end insulation layers (11). The upper and lower end surfaces of the high-voltage coil (3) are sequentially provided with high-voltage end insulation layer one (12) and high-voltage end insulation layer two (13) from inside to outside. The outer end of the soft corner ring (10) is laid on the outer side surface of the high-voltage end insulation layer two (13), and the outer side surface of the outer end of the soft corner ring (10) is flush with the outer side surface of the low-voltage end insulation layer (11). The outer side surface of the outer end of the soft corner ring (10) and the outer side surface of the low-voltage end insulation layer (11) are provided with an iron yoke insulation layer (14).

5. The main void insulation structure of a 35 kV class laminated winding oil immersed transformer as claimed in claim 4, wherein, the said main void insulation structure is made of a combination of pressboard and paper. The thickness of the low-voltage end insulation layer (11) is d1=7mm, and the thickness of the high-voltage end insulation layer one (12) is d6=10mm.

6. The main void insulation structure of a 35 kV class laminated winding oil immersed transformer as claimed in claim 1, wherein, The layers of the low-voltage coil (2) and the high-voltage coil (3) are annularly spaced by a plurality of support bars (3) for heat dissipation. The layers of the low-voltage coil (2) or the high-voltage coil (3) form a plurality of longitudinal oil channels (15).

7. The main void insulation structure of the 35 kV class laminated winding oil-immersed transformer according to any one of claims 1 to 6, characterized by, The plurality of the first struts 5, the first paperboard layer 6, the second paperboard layer 7, the third paperboard layer 8, the plurality of the second struts 9 and the soft corner ring 10 are all fixed on the outer circumferential side of the core 1 by binding and covering.

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